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71.
In the case of plastics containing brominated flame retardants, various brominated organic compounds, including polybrominated dibenzodioxins and dibenzofurans, are yielded when they are degraded. In order to reduce the hazard that might be generated during after-live treatment, the behaviour of flame retarded high-impact polystyrene containing decabromo diphenylether and antimony oxide (Sb2O3), was investigated using several heating programs. It was found that the separation of the thermal process into two steps divided at 330?°C makes it possible to obtain an oil fraction rich in brominated compounds at low temperatures and an oil fraction depleted in brominated compounds at high temperatures. The low temperature oil contained a high concentration of SbBr3 and dibromodibenzofurans. Various brominated compounds with a low volatility and 1-bromo-1-phenylethane from the reaction of HBr with styrene were among the substances in the high temperature oil. The concentration of brominated compounds was reduced from 6?wt% for degradation in a single step to below 1?wt% in the high temperature oil in the two step process.  相似文献   
72.
Unrusted high carbon iron filings (HCIF) were contacted sequentially with successive aliquots of aqueous 2-chloronaphthalene (2-CN), i.e., in semi-batch mode, both in well-mixed and poorly-mixed conditions. Aqueous concentration of 2-CN and the dehalogenation by-product naphthalene (N) were monitored at the beginning and end of each 2-CN addition cycle. Experimental data was modeled using the 2-CN dehalogenation and adsorption/desorption rate constants determined from batch experiments involving 2-CN and a similar HCIF sample. Model predictions for the semi-batch experiments matched quite well with the experimental data in both well-mixed and poorly-mixed cases. Further, it was experimentally demonstrated that adsorption and hence accumulation of N on HCIF surface did not substantially hinder either 2-CN adsorption or dehalogenation under the conditions examined in this study. Continuous transport of water containing 0.5 μmol L?1 2-CN through a 1.0-m thick unrusted HCIF layer was simulated at superficial velocities of 0.01 and 0.10 m h?1. Both simulations indicated nearly complete removal of 2-CN in the HCIF layer. This study suggests that HCIF can be used as a potential reactive material in permeable reactive barriers (PRBs) for in situ remediation of groundwater contaminated with 2-CN.  相似文献   
73.
Summary Automobiles are a necessary evil, while they have made living easy and convenient, they have also made human life more complicated and vulnerable to both toxic emissions and an increased risk of accidents. Urban people are most affected and amongst the worst sufferers are traffic policemen who are particularly close to the fumes of automobile exhaust. Studies made in Jaipur, India, indicate that there is high rate of occurrence of respiratory, digestive, ocular and skin problems amongst the traffic policemen and a significant number of them become victims of lung disorders in the very first few months of their posting to a traffic department. Traffic policement everywhere should wear pollution masks for their own safety and to arouse public awareness of the risk of automobile pollution.Dr Rajiv K. Sinha is Assistant Professor in Human Ecology at the Indira Gandhi Centre of Human Ecology, Environmental and Population Studies at the University of Rajasthan. He was formerly a teaching assistant at University of Windsor,  相似文献   
74.
The inhibition of seedling growth and nitrate reductase activity in 5 d old Vigna radiata (L.) Wilczek cv. Pusa Baisakhi in the presence of 1.0 mM lead acetate increased drastically, if NaCl (6 and 12 EC) was also present in the nutrient media along with the metal salt. Correspondingly higher endogenous Na+ levels were accumulated in the roots and leaves of seedlings in presence of the two stresses. On the other hand, the levels of endogenous lead get reduced in presence of NaCl in both the roots and leaves. Roots accumulated more Pb2+ and Na+ than the leaves. The two stresses affect more drastically in the additive or even synergistic manner during the early growth phase of the seedlings.  相似文献   
75.
Every two months of 1992, as well as on three occasions in 1994-1995, we obtained leaf samples together with samples of surrounding air from eight well-watered and fertilized sour orange (Citrus aurantium L.) trees that were growing out-of-doors at Phoenix, Arizona, USA. These trees had been planted in the ground as small seedlings in July of 1987 and enclosed in pairs by four clear-plastic-wall open-top chambers of which two have been continuously maintained since November of that year at a CO2 concentration of 400 micromol mol(-1) and two have been maintained at 700 micromol mol(-1). In September 2000, we also extracted north-south and east-west oriented wood cores that passed through the center of each tree's trunk at a height of 45 cm above the ground. Stable-carbon isotope ratios (13C/12C) derived from these leaf, wood and air samples were used to evaluate each tree's intrinsic water-use efficiency (iWUE). The grand-average result was an 80% increase in this important plant parameter in response to the 300 micromol mol(-1) increase in atmospheric CO2 concentration employed in the study. This increase in sour orange tree iWUE is identical to the long-term CO2-induced increase in the trees' production of wood and fruit biomass, which suggests there could be little to no change in total water-use per unit land area for this species as the air's CO2 content continues to rise. It is also identical to the increase in the mean iWUE reported for 23 groups of naturally occurring trees scattered across western North America that was caused by the historical rise in the air's CO2 content that occurred between 1800 and 1985.  相似文献   
76.
A few physico-chemical and bacteriological parameters on certain locations of the river Torsa was studied. The major characteristics of Torsa river water were high alkalinity, high concentration of free ammonia with respect to albuminoid ammonia and the presence of bacteria of fecal origin. Marked seasonal variations of the parameters were also observed.  相似文献   
77.
The correlation study of secondary aerosol (nitrate and sulfate) with RPM in ambient air at different traffic junctions of Vadodara city is reported. RPM was analyzed using Ion Chromatography technique and measured the level of nitrate and sulfate in ambient air. The correlation studies of these particulates with RPM have been established. The average concentration of sulfate and nitrate in ambient air was found 35.74 microg/m3 and 24.22 microg/m3, which ranged of 5.33-84.69 and 1.93-77.86 microg/m3 respectively. The correlation of RPM and SO4 (r = 0.813, P<0.01), RPM-NO3 (r = 0.5549, P<0.01) and SO4-NO3 (r = 0.6133, P<0.01) were found significant. The presence of sulfate and nitrate in RPM is 8.25% and 5.60% . The pH of water extract of RPM averaged 6.81, which ranged 6.17-7.28. Regression analysis result showed that the relationship between RPM-SO4 was significantly (R2=0.66215) correlated. This indicate that probably the secondary aerosols such as nitrate and sulfate in excess may cause irritation and increasing lung disease.  相似文献   
78.
Most environmental professionals and decision-makers, and certainly the public at large, hold the view that the integrity of earth’s natural environment will be conserved for posterity and sustainable development achieved if all the nations rigorously enforced their environmental and emission standards. It is argued in this paper that this view, sincerely held by many as an “axiomatic truth,” is mistaken and misplaced. This is because as a biogeochemical entity the Earth has limited self-regenerative capacity (SRC) to cope with anthropogenic pollution, and all kinds of environmental problems ensue when that limit is exceeded. Indeed, mounting environmental problems now occurring on all fronts amply testify to the fact that the limit has already been exceeded. They also provide necessary and sufficient proof that environmental and emission standards have been woefully inadequate for protecting earth’s natural environment and life-support systems. It is argued that true global environmental sustainability will be achieved, paving the way to true global sustainable development, if and only if global environmental and emission standards are set so that global anthropogenic pollution does not exceed the limit of earth’s natural SRC to cope with such pollution. These and related issues are discussed in this paper. A simple mathematical model using basic mathematics is also presented to explain how the phenomenon of “positive feedback” works in some of the environmental problems to exacerbate environmental degradation and progressively to erode nature’s SRC.
Bhaskar NathEmail:
  相似文献   
79.
Sinha S  Gupta AK 《Chemosphere》2005,61(8):1204-1214
The plants of Sesbania cannabina Ritz grown on different amendments of fly ash (FA), have shown a high accumulation of metals (Fe, Mn, Zn, Cu, Pb and Ni). The highest accumulation of Fe the and lowest level of Ni were recorded in these plants. The different amendments of fly ash with garden soil (GS) were extracted with DTPA and the levels of metals were found to be decreased with an increase in fly ash application ratio from 10% to 50% FA. The analysis of the results showed an increase in the level of malondialdehyde (MDA) content of the roots for all the exposure periods. The maximum increases of 136% (roots) and 120% (leaves) were observed in MDA content at 100% FA after 30 d of growth of the plant, compared to GS. The level of antioxidants was found to increase for all the exposure periods in the roots of the plants to combat metal stress. At 30 d, the maximum increase of 57% (ascorbic acid) and 78% (free proline) was observed in the roots of the plants grown on 100% and 10% FA, respectively, as compared to their respective GS. At 90 d, a maximum increase of 42% (cysteine) and 117% (NPSH) was recorded in the roots of the plants grown on 25% and 100% FA, respectively, as compared to their respective GS. In leaves, a significant increase in antioxidants i.e. cysteine, NPSH and free proline content was recorded after 30 d, whereas no such trend was observed for the rest of the exposure periods. The chlorophyll and carotenoid contents increased with an increase in the FA amendment ratio from 10% to 50% FA for all the exposure periods as compared to GS. In both roots and leaves, the level of protein content increased in all the amendments and 100% FA at 30 d as compared to GS. Thus, there is a balance in the level of MDA content and level of antioxidants in the plants at 90 d. In view of its tolerance, the plants may be used for phytoremediation of metals from fly ash contaminated sites and suitable species for plantation on fly ash land fills.  相似文献   
80.
Summary Iron and steel have been used in India since ancient times (possibly as early as 5000 BC). There are several references to the use of iron and steel in the Vedic literatures. The rust and corrosionfree iron pillar of Qutub Minar in Delhi, built 1500 years ago and the steel girders used in the temples of Orissa around AD 700–1200 still bear the testimony of these early industries. Steels are in great demand today but the large steel plants provide a limited range of steel mostly consumed in building and construction activities. In India, heavy machine tools, locomotives, automobiles, aviation, ship building and engineering tools require super grade steels with various specifications and these are met by mini iron and steel industrial plants. There are approximately 160 such plants mostly situated in big cities and towns. There are several economic and ecological advantages of these mini steel plants. They mostly use iron and steel scrap and other kinds of iron wastes from large industries as their raw material, contrary to the large plants which use iron ores as primary raw materials, the extraction processing and utilization of which involves severe environmental damage by way of deforestation and air and water pollution. Mini steel plants consume much less water and energy. The government of India has given a number of incentives to the mini steel industries by way of exemption from income tax, custom and excise duties, depreciation and investment allowances and rebates on charges for consumption of water and electricity.Dr Rajiv K. Sinha is an assistant professor in human ecology at the University of Rajasthan. Mr V.N. Bhargava is an engineer employed at the Research and Development Division of National Engineering Industries, Khatipura Road, Jaipur 302006, India.  相似文献   
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